An aluminum alloy hub is one of important appearance components on a vehicle, so each automobile manufacturer establishes extremely strict standards for the quality of the front face of the hub, and it requires that the surfaces of products after a coating process cannot have any quality defects. At present, the aluminum alloy hub mainly utilizes a low-pressure casting forming technique, so defects, such as white spots, segregation and the like, usually occur on the surfaces of finish turned products during actual production, which belongs to a remarkable apparent defect problem; and the products with these defects occupy a large proportion of production wastes. Field analysis suggests that the main reason for these defects is cooling nonuniformity of the bottom mold. The existing bottom mold mainly utilizes a point cooling manner, cooling points in such cooling manner are constant, and the mold temperature of parts corresponding to air tubes is quickly reduced; meanwhile, a temperature distribution trend gradually increasing from the center of each cooling point to the outside is formed, but no stable and uniform temperature gradient is formed on the surface of the whole mold; therefore, a local feeding insufficiency situation occurs, and finally, these defects, such as the white spots, the segregation and the like, occur on slowly cooled parts of a casting, resulting in production wastes directly.
By combining the above-mentioned analysis, it is necessary to optimize and improve the existing mold cooling structure during production in order to solve the problem that the defects, such as the white spots, the segregation and the like, are liable to occur on the surface of the hub; and due to effective control on a casting process, the appearance quality of the final products is improved, and the rejection rate is reduced.